JP2005262432A - Method of manufacturing large-size substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a large-size substrate such as a substrate for a large-size photomask of high parallelism and high flatness by an economically advantageous processing method, by securing a stable processing speed, without requiring polishing of a post-process, without causing fragile breaking in partial processing. <P>SOLUTION: This manufacturing method of the large-size substrate enhances the flatness and the parallelism of the large-size substrate, by partially removing a projecting part and a thick part of the substrate by a processing tool on the basis of its data, by measuring the flatness and the parallelism of the large-size substrate having the diagonal length of 500 mm or more in advance by vertically holding the large-size substrate. The manufacturing method of the large-size substrate is characterized in that the processing tool is formed into a structure for jetting slurry on the substrate by simultaneously carrying the slurry of suspending particulates in the water on the compressed air. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a large-sized substrate suitable as a synthetic quartz glass substrate for a photomask, particularly a substrate used in a TFT liquid crystal panel.

  In general, a TFT liquid crystal panel employs an active method in which liquid crystal is sealed between an array side substrate in which TFT elements are incorporated and a substrate on which a color filter is mounted, and the voltage is controlled by the TFT to control the alignment of the liquid crystal. It has been.

  At the time of manufacturing the array side substrate, a method is employed in which a master plate on which a circuit called a large photomask is drawn is baked in layers on a non-alkali mother glass by light exposure. On the other hand, the color filter side substrate is also manufactured by a method using lithography called a dye impregnation method. Both the array side and color filter side substrates require large photomasks, and synthetic quartz glass with a small linear expansion coefficient is mainly used as the material for these large photomasks in order to carry out accurate exposure. ing.

  Until now, liquid crystal panels have advanced from VGA to SVGA, XGA, SXGA, UXGA, and QXGA, and it is said that the resolution of 100 ppi (pixel per inch) class to 200 ppi class is necessary. The exposure accuracy, especially the overlay accuracy, is becoming stricter.

  Panels are also manufactured using a technique called low-temperature polysilicon, but in this case, a driver circuit or the like is baked on the outer periphery of the glass separately from the panel pixels. Exposure is required.

  On the other hand, it has been found that the shape of a large photomask substrate affects the exposure accuracy. For example, as shown in FIG. 1, when exposure is performed using two large photomask substrates having different flatness, the pattern is deviated due to the difference in optical path. That is, in FIGS. 1A and 1B, the dotted line indicates the path when the mask is in an ideal plane when the light travels straight, but the light is shifted as shown by the solid line in the figure. Further, in the case of an exposure machine that uses an optical system for focusing, there is also a phenomenon that the focus position is shifted from the exposure surface and the resolution is deteriorated. For this reason, a high-flatness photomask substrate is desired for further high-precision exposure.

  In addition, there is a demand for a large-sized photomask substrate with a diagonal length of 1500 mm for the purpose of improving the productivity of the panel by performing multiple exposures in a single exposure, and large size and high flatness are simultaneously achieved. It has been demanded.

  In general, large-sized photomask substrates are manufactured by wrapping plate-like synthetic quartz with a slurry of free abrasive grains such as alumina suspended in water, removing surface irregularities, and then using cerium oxide or the like. Polishing is performed using a slurry in which an abrasive is suspended in water. As a processing apparatus used at this time, a double-sided processing machine, a single-sided processing machine, or the like is used.

  However, in these processing methods, the repulsive force against the elastic deformation that occurs when the substrate itself is pressed against the processing platen is used for correcting the flatness, so that the repulsive force is remarkably increased when the substrate size is increased. As a result, the ability to remove the gentle irregularities on the surface of the substrate is reduced. FIG. 2A shows the shape of the substrate 1 when held vertically, and FIG. 2B shows that the shape of the substrate 1 being processed follows the surface plate during processing. (C) shows the repulsive force against the elastic deformation of the substrate 1 at this time, and the amount (ΔP) of this force is processed more than other portions.

  It is also common practice to improve flatness using a surface grinding apparatus. Generally, the surface grinding apparatus employs a method in which a workpiece is passed at a fixed interval between the workpiece setting table and the processing tool, and a portion of the workpiece exceeding the fixed interval is removed by the processing tool. . In this case, if the flatness of the back surface of the work piece is not obtained, the work surface is pressed against the work piece setting table by the grinding resistance of the processing tool. As a result, the flatness of the front surface follows the flatness of the back surface. Therefore, the flatness cannot be improved at present.

  In order to solve these problems, Japanese Patent Application Laid-Open No. 2003-292346 (Patent Document 1) proposes a method for processing a substrate for a large photomask in which a convex portion and a thick portion of the substrate are partially removed by a partial processing tool. ing. However, in the method of using grinding or sandblasting as a partial processing tool, brittle fracture may occur on the substrate surface due to partial processing, and there is a possibility that minute crack-like defects may occur on the substrate surface. In order to remove the defects, it was necessary to perform polishing with a double-side polishing apparatus or a single-side polishing apparatus after partial processing. In addition, since the polishing apparatus used after partial processing does not deteriorate the substrate flatness and thickness variation accuracy due to polishing, it is necessary to maintain and manage the polishing machine accuracy. Furthermore, if the substrate flatness or thickness variation decreases due to polishing after partial processing such as sandblasting, and it deviates from the desired numerical value, it is necessary to perform polishing after partial processing such as sandblasting again. Therefore, there has been a demand for a processing method for accuracy correction that does not involve brittle fracture and does not require subsequent polishing.

  In addition, a processing tool with an abrasive cloth affixed to a surface plate so as not to cause brittle fracture has been proposed, but since the processing speed gradually decreases due to abrasive cloth wear accompanying processing, the processing tool is frequently used. Had to be replaced and needed manpower and time. Therefore, there has been a demand for an economically advantageous processing method that does not involve brittle fracture in partial processing, does not require subsequent polishing, and can secure a stable processing speed.

JP 2003-292346 A

  The present invention has been made in view of the above circumstances, does not involve brittle fracture in partial processing, does not require subsequent polishing, can secure a stable processing speed, and is highly flat by an economically advantageous processing method. An object of the present invention is to provide a method for manufacturing a large-sized substrate such as a large-sized photomask substrate.

  As a result of intensive studies to achieve the above object, the present inventors have previously determined the flatness of one or both sides of a large substrate having a diagonal length of 500 mm or more, preferably the flatness and parallelism of both surfaces, preferably a large substrate. When measuring by holding vertically and increasing the convexity and parallelism on the flatness measurement surface of the large substrate based on the data, thick portions on both sides are partially removed with a processing tool, and the large substrate In the manufacturing method of a large substrate that increases the flatness and, if necessary, the parallelism, as a partial processing tool, fine particles such as cerium oxide, aluminum oxide, silicon oxide, etc. with a particle diameter of 3 μm or less are preferably suspended in water in compressed air. Large-scale photo with high flatness economically without causing brittle fracture on the substrate surface. And it found that it is possible to obtain a large substrate such as a substrate for disk, in which the present invention has been accomplished.

Therefore, the present invention provides the following large substrate manufacturing method.
(I) The flatness of one or both sides of a large substrate having a diagonal length of 500 mm or more is measured in advance, and the convex portion on the flatness measurement surface of the large substrate is partially removed by a processing tool based on the data. In the manufacturing method of a large substrate for improving the flatness of the large substrate, the processing tool has a structure in which a slurry of fine particles suspended in water is entrained in compressed air and ejected onto the substrate. A method for producing a large-sized substrate.
(II) The flatness and parallelism of both surfaces of the large substrate are measured, and the convex and thick portions on both surfaces of the large substrate are removed by a processing tool based on the data. A manufacturing method for large substrates.
(III) The method for producing a large substrate according to (I) or (II), wherein the fine particles are cerium oxide, silicon oxide or aluminum oxide.
(IV) The method for producing a large substrate according to any one of (I) to (III), wherein the average particle size of the fine particles is 3 μm or less.
(V) The method for producing a large substrate according to any one of (I) to (IV), wherein the compressed air has a pressure of 0.05 to 0.5 MPa.
(VI) The method for producing a large substrate according to any one of (I) to (V), wherein the large substrate is a synthetic quartz glass substrate.
(VII) The method for producing a large substrate according to any one of (I) to (VI), wherein the large substrate is an array side substrate of a TFT liquid crystal.

  According to the method for manufacturing a large-sized substrate of the present invention, since it is possible to perform processing without causing brittle fracture on the substrate surface, labor and time spent for maintaining mechanical accuracy in the subsequent polishing step are unnecessary, and economically. A large substrate with high flatness can be obtained.

  The large substrate of the present invention is preferably a glass substrate, particularly a synthetic quartz glass substrate, which is used as a photomask substrate, a TFT liquid crystal array side substrate, etc., and has a diagonal length of 500 mm or more, preferably 500. It has a dimension of ˜2,000 mm. The shape of the large substrate may be a square, a rectangle, a circle, or the like. In the case of a circle, the diagonal length means a diameter. The thickness of the large substrate is not particularly limited, but is preferably 1 to 20 mm, particularly 5 to 12 mm.

  In the production method of the present invention, first, the flatness of the surface of a large substrate to be flattened, that is, one or both surfaces (front and back surfaces) is measured. When considering the parallelism of a large substrate, the flatness and parallelism of both surfaces are measured. In order to shorten the processing time, it is preferable that the plate material used as a raw material is first subjected to mirror finishing with a double-side polishing apparatus or a single-side polishing apparatus so that the flatness and / or parallelism is adjusted as much as possible. The present invention can be applied even when the substrate surface is rough like a lapping surface, but it is economically disadvantageous because the processing time becomes long. In addition, the measurement of flatness and parallelism can be calculated | required, for example using Kuroda Seiko Co., Ltd. flatness tester (FTT-1500). In addition, it is recommended that the flatness and parallelism be measured by holding the plate vertically in order to eliminate the deformation of the plate material.

Next, this measurement data is used to measure the height data and parallelism at each point in the flatness measurement surface of the substrate (front and back surfaces when the flatness of both surfaces is measured). It is stored in the computer as data. Based on this data, the surface of the substrate to be flattened, that is, the surface to be flattened (in the case of both sides) is corrected in order to correct the flatness of the flatness measurement surface (front and back if both sides are flattened). If this is the case, the least square plane calculated for each surface) is used as a reference plane, the machining removal amount is calculated so that the height matches the lowest point in the plane to be flattened, and the machining tool dwell time is calculated.
Further, when increasing the parallelism, the parallelism of the substrate that should be obtained after the flat processing is calculated, and in order to correct this parallelism, the thickness matches the portion where the thickness of the substrate surface is calculated to be the thinnest. Thus, the machining removal amount is calculated, and the residence time of the machining tool is calculated.

  In this case, for example, if the back surface is flat, this is used as a reference surface, the residence time is calculated so that the surface is parallel to the back surface, and the surface processing is performed from the residence time result for flattening the surface. The final residence time of the processing tool when performing may be obtained, but more preferably, a plane that should be parallel to the substrate is assumed, and this is used as a reference surface, and the substrate surface is the thinnest with respect to each of the front and back surfaces. Calculate the residence time of the front and back sides so that the thicknesses of the other parts of the front and back sides match the both sides (front and back) locations corresponding to the part, and finally the residence time for flattening the front and back sides. Calculate the final processing removal amount in each part to correct the flatness and parallelism of both sides, and calculate the residence time of the processing tool, based on the above final residence time when processing both sides, On each side With or faster or slow down the movement speed of the processing tool to control the residence time, it is preferable to carry out the processing.

  Note that the above method performs the desired processing by controlling the moving speed of the processing tool, but as described later, instead of controlling the moving speed of the processing tool, the air blowing pressure from the processing tool May be performed while controlling both the moving speed of the processing tool and the air blowing pressure.

  Here, the processing tool used in the present invention has a structure in which a slurry in which fine particles are suspended in water can be sprayed onto a substrate using air pressure. When fine particles are not suspended in water, that is, when dry sandblasting is used, the fine particles tend to aggregate and form large particles as the particle size of the fine particles is reduced, and these large particles collide with the substrate surface. Then, it becomes easy to raise | generate a brittle fracture.

  In the above processing tool, the fine particles suspended in water are not particularly limited, but cerium oxide, silicon oxide, and aluminum oxide are preferable. Moreover, it is preferable that the average particle diameter of this microparticle is 3 micrometers or less, More preferably, it is 0.5-2 micrometers. If the average particle diameter exceeds 3 μm, micro cracks may be generated on the substrate surface due to processing, and if it is less than 0.5 μm, the removal speed may be slow and processing may take time. In the present invention, the average particle diameter can be determined by a laser light diffraction particle size distribution measuring device, a Coulter counter, or the like.

  The amount of fine particles in the slurry is preferably 2 to 30% by mass, particularly 5 to 15% by mass. If the amount of fine particles is too small, processing may take a long time. If the amount is too large, dispersion of the fine particles in water may be insufficient, and aggregated particles may be easily generated on the substrate surface. Moreover, this slurry can be prepared according to a conventional method. Furthermore, it is also possible to add a surfactant or the like to the slurry to disperse the fine particles, to prevent drying, and to improve cleaning properties.

  The slurry is jetted onto the substrate using air pressure. The air pressure is related to the fine particles used and the distance between the processing tool and the substrate, and is not uniquely determined, and is preferably adjusted in view of the removal rate and the presence or absence of brittle fracture. 0.5 MPa, particularly 0.05 to 0.3 MPa. If the air pressure is less than 0.05 MPa, processing may take time, and if it exceeds 0.5 MPa, microcracks may be generated on the substrate surface.

In addition, the structure for injecting slurry onto the substrate using air pressure is not particularly limited. For example, a double pipe is used to supply slurry from the center and supply air from the outer periphery. Can do.
In this case, the supply amount of slurry and air varies depending on the nozzle size, but when the slurry supply amount is Aml / min and the air supply amount is BNm ³ / min, A / B is 20 to 500, particularly 50 to 300 is preferable. If A / B is less than 20, processing may take time, and if it exceeds 500, microcracks may be generated on the substrate surface.

  As the parallelism correction and flatness correction processing methods, for example, processing can be performed using the apparatus shown in FIG. Here, in the figure, 10 is a substrate holding table, and 11 is a processing tool. Reference numeral 1 denotes a substrate. The processing tool has a structure that can be arbitrarily moved in the X and Y directions, and the movement can be controlled by a computer. Processing can also be performed with an X-θ mechanism.

  When processing the flatness of a desired surface (one side or both sides) of a large-sized substrate using such a processing tool, preferably when processing parallelism further, each part calculated based on the measurement data described above is used. In accordance with the residence time of the processing tool, the convex portion and the thick portion of the desired surface of the large substrate are partially removed by the processing tool.

  Here, the convex part means a part higher than the lowest part in the surface to be flattened when the least square plane is used as a reference plane, and a thick part means a thickness when parallelism processing is performed. This is the thicker part than the part that is calculated to be the thinnest.

  In this case, the part where the air blowing pressure from the processing tool is constant and the removal amount is large will slow down the moving speed of the processing tool and lengthen the residence time, while the part where the removal amount is small will be processed By increasing the moving speed of the tool and shortening the residence time, it is possible to perform processing while controlling the residence time.

  The purpose of pressure control is to keep the moving speed of the processing tool constant and increase the air blowing pressure from the processing tool at the calculated part when the removal amount is large, and decrease at the calculated part when the removal amount is small. Can be achieved.

  In the present invention, the processing removal speed varies depending on the particle size of the suspended particles, the substrate material, the air pressure, the distance between the processing tool and the substrate surface, etc., so the processing characteristics are grasped using the processing tools and processing conditions used in advance. In addition, it is necessary to reflect the residence time of the processing tool and the air blowing pressure.

Here, it is preferable to process the front and back surfaces to increase the flatness of the front and back surfaces. Moreover, it is preferable to process so that parallelism may also be improved.
According to the present invention, a large glass substrate having a flatness of 10 to 50 μm, particularly 10 to 30 μm, and a parallelism of 2 to 30 μm, particularly 2 to 15 μm, before and after the above processing is obtained. Can be made to have a flatness of 2 to 20 μm, particularly 2 to 10 μm, and a parallelism of 1 to 20 μm, particularly 1 to 10 μm (the flatness of the front and back after processing). Can be set to 1/2 to 1/20, particularly 1/5 to 1/20 of the flatness of the front and back surfaces before processing, and the parallelism after processing is 1/2 to 1 of the parallelism before processing. / 10, especially 1/5 to 1/10). In addition, although the above is a case where both the front surface and back surface are processed, when the flatness of only the surface is required, it is sufficient to process only the surface.
Further, after the above processing, post-polishing is not always necessary, and for surface polishing, polishing by the above processing can be used as final polishing.

  In the manufacturing method of the present invention, since there is no brittle fracture when selectively removing the convex portion and the thick portion of the substrate by the above method, it is not necessary to perform a polishing process after this, so that the mechanical accuracy control in the subsequent process can be performed. In addition to saving, a high flatness substrate can be obtained in a short time.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the following examples, the flatness tester (FTT-1500) manufactured by Kuroda Seiko Co., Ltd. was used for the measurement of parallelism and flatness.

[Example 1]
A synthetic quartz substrate having a size of 520 × 800 mm (diagonal length: 954 mm) and a thickness of 10.5 mm was processed with a double-sided lapping machine that performs planetary motion using GC # 600 manufactured by Fujimi Abrasive Co., Ltd. Thereafter, double-side polishing was performed using cerium oxide having an average particle diameter of 1 μm to prepare a raw material substrate. The accuracy of this raw material substrate was such that the surface flatness was 20 μm, the back surface flatness was 22 μm, and the parallelism was 4 μm, and the central portion had a high shape.

Next, this raw material substrate was mounted on the substrate holder 10 of the apparatus shown in FIG. The processing tool 11 has a structure that can move substantially parallel to the substrate holding table in the X and Y axis directions, and the distance between the slurry blowing port of the processing tool 11 and the surface of the substrate 1 is set to 100 mm.
Further, the processing tool 11 is a double tube, and has a structure in which slurry is supplied from the center portion and air is supplied from the outer peripheral portion, and the slurry is sprayed onto the substrate together with air. Here, the slurry was prepared to a slurry of 10% by mass by suspending cerium oxide fine particles having an average particle diameter of 1 μm in water.

As shown in FIG. 4, the machining method was such that the machining tool was continuously moved parallel to the X axis and moved at a pitch of 10 mm in the Y axis direction. The slurry supply rate during processing was 400 ml / min, the air pressure was 0.3 MPa, and the air supply rate was 2 Nm ³ / min. The processing speed under these conditions was 1 μm / min from the value measured in advance, and was made smaller toward the outer periphery. The moving speed of the processing tool is 50 mm / sec at the part where the removal amount is the smallest in the calculation, and the moving speed at each part of the substrate is the required residence time of the processing tool at each part of the substrate from the processing speed and processing profile The moving speed was calculated from this, the processing position was moved by moving the processing tool, and the both surfaces of the substrate were processed.
The precision of the substrate after processing was a surface flatness of 3.6 μm, a back surface flatness of 3.7 μm, and a parallelism of 2.1 μm, and there was no brittle fracture.

[Example 2]
The same procedure as in Example 1 was performed except that the fine particles were cerium oxide having an average particle diameter of 3 μm.

[Example 3]
The same procedure as in Example 1 was performed except that the fine particles were aluminum oxide having an average particle diameter of 2 μm.

[Example 4]
The same procedure as in Example 1 was performed except that the fine particles were silicon oxide having an average particle diameter of 2 μm.

[Example 5]
The same operation as in Example 1 was performed except that the air pressure was 0.5 MPa.

[Example 6]
The same procedure as in Example 1 was performed except that the raw material substrate had a surface flatness of 22 μm, a back surface flatness of 24 μm, and a parallelism of 15 μm.

  The results of Examples 1 to 6 are shown in Table 1.

[Comparative Example 1]
The procedure was the same as in Example 1, except that the fine particles were aluminum oxide having an average particle size of 10 μm and the fine particles were sprayed in a dry state without being suspended in water.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that the fine particles were cerium oxide having an average particle diameter of 1 μm and the fine particles were sprayed in a dry state without being suspended in water.

  The results of Comparative Examples 1 and 2 are shown in Table 2.

It is a figure explaining the optical path at the time of exposing to the board | substrate for photomasks, (A) shows the optical path of a board | substrate with a concave upper surface, (B) shows a convex surface. A mode when polishing a substrate with a processing surface plate is shown, (A) is a front view showing the shape of the substrate when held vertically, (B) is a front view showing a state following the surface plate during processing, (C ) Is an explanatory diagram showing the repulsive force on the lower surface plate at that time. It is a perspective view which shows the outline | summary of a processing apparatus. It is a perspective view which shows the movement aspect in a processing tool.

Explanation of symbols

1 Substrate 10 Substrate holder 11 Processing tool

Claims (7)

  The flatness of one or both sides of a large substrate having a diagonal length of 500 mm or more is measured in advance, and the convex portion on the flatness measurement surface of the large substrate is partially removed by a processing tool based on the data, and the large substrate In the manufacturing method of a large substrate for improving the flatness of the substrate, the processing tool has a structure in which compressed air is ejected onto the substrate together with a slurry in which fine particles are suspended in water. A method for manufacturing a large substrate.   2. The large substrate according to claim 1, wherein the flatness and parallelism of both surfaces of the large substrate are measured, and the convex portions and the thick portions on both surfaces of the large substrate are removed by a processing tool based on the data. Production method.   3. The method for producing a large substrate according to claim 1, wherein the fine particles are cerium oxide, silicon oxide, or aluminum oxide.   The method for producing a large substrate according to claim 1, 2 or 3, wherein the average particle diameter of the fine particles is 3 µm or less.   The method for producing a large substrate according to any one of claims 1 to 4, wherein the compressed air has a pressure of 0.05 to 0.5 MPa.   The method for producing a large substrate according to any one of claims 1 to 5, wherein the large substrate is a synthetic quartz glass substrate.   7. The method for manufacturing a large substrate according to claim 1, wherein the large substrate is a TFT liquid crystal array side substrate.

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